Broadband Back Action Cancellation in a Dichromatic Variational Measurement

TL;DR

This paper demonstrates a method to cancel quantum back action noise in measurements of mechanical oscillators by using a dichromatic field, enabling broader bandwidth and improved sensitivity.

Contribution

It introduces a novel technique employing dichromatic fields to achieve broadband back action cancellation in quantum measurements.

Findings

Successful subtraction of quantum back action noise.

Enhanced measurement bandwidth achieved.

Potential for improved quantum sensing applications.

Abstract

Quantum back action imposes fundamental sensitivity limits to the majority of quantum measurements. The effect results from the unavoidable contamination of the measured parameter with the quantum noise of a meter. Back action evading measurements take advantage of the quantum correlations introduced by the system under study to the meter and allow overcoming the fundamental limitations. The measurements are frequently restricted in their bandwidth due to a finite response time of the system components. Here we show that probing a mechanical oscillator with a dichromatic field with frequencies separated by the oscillator frequency enables independent detection and complete subtraction of the measurement noise associated with the quantum back action.